Methods for restoring blood flow within blocked vasculature

ABSTRACT

The devices and methods described herein relate to clearing of blockages within body lumens, such as the vasculature, by addressing the frictional resistance on the obstruction prior to attempting to translate and/or mobilize the obstruction within the body lumen.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/942,547, filed Apr. 1, 2018, which is a continuation of U.S. patentapplication Ser. No. 14/038,461, filed Sep. 26, 2013, now U.S. Pat. No.9,931,128, which is a continuation of U.S. patent application Ser. No.11/684,546, filed Mar. 9, 2007, which is a continuation of U.S. patentapplication Ser. No. 11/671,450, filed Feb. 5, 2007, which is anon-provisional of U.S. Provisional Application No. 60/765,496, filedFeb. 3, 2006, each of which are incorporated by reference herein intheir entireties.

FIELD OF THE INVENTION

The devices and methods described herein relate to clearing of blockageswithin body lumens, such as the vasculature, by addressing thefrictional resistance on the obstruction prior to attempting totranslate the obstruction within the body lumen. In one variation, thedevices and methods described below may treat conditions of ischemicstroke by remove blockages within arteries leading to the brain.Accordingly, variations of such methods and devices must navigatetortuous anatomy and vasculature without causing unacceptable damage tothe anatomy. Also, the devices and methods first secure and surround theobstruction (such as a clot) prior to significantly moving the clotwithin the anatomy.

BACKGROUND OF THE INVENTION

Ischemic stroke occurs when a blockage in an artery leading to the braincauses a lack of supply of oxygen and nutrients to the brain tissue. Thebrain relies on its arteries to supply oxygenated blood from the heartand lungs. The blood returning from the brain carries carbon dioxide andcellular waste. Blockages that interfere with this supply eventuallycause the brain tissue to stop functioning. If the disruption in supplyoccurs for a sufficient amount of time, the continued lack of nutrientsand oxygen causes irreversible cell death (infarction). Accordingly,immediate medical treatment of an ischemic stroke is critical for therecovery of a patient.

The infarction may not develop or may be greatly limited, given a rapidclearing of the blockage to reestablish the flow of blood. However, ifleft untreated, ischemic stroke may lead to the permanent loss of braintissue, and can be marked by full or partial paralysis, loss of motorcontrol, memory loss, or death.

Several different diseases may lead to an ischemic stroke. Typically,deposition of cholesterol (artheroselerosis), formation of blood clots,or other objects in the vessels may disrupt blood flow and lead toischemic stroke. Furthermore, the substances that cause the blockagesmay break free from larger vessels outside the brain and become lodgedwithin narrower arteries closer to the brain embolism).

Ischemic stroke may be divided into thrombotic strokes and embolicstrokes. A thrombotic stroke occurs when the building and rupturing ofatheromatous plaque within the brain blocks cerebral arteries.Clinically referred to as cerebral thrombosis or cerebral infarction,this condition represents approximately 10% of all strokes. An embolicstroke occurs when a clot or emboli forms somewhere other than in thebrain, such as in the cervical carotid artery or in the heart, andtravels in the bloodstream until the clot becomes lodged and can nottravel any further. When such a condition occurs in the arteriessupplying the brain, the condition results in almost immediate physicaland neurological effects.

While these are the most common causes of ischemic stroke, there aremany other possible causes. Examples include use of drugs, trauma to theblood vessels of the neck, or blood clotting disorders.

Apart from surgical techniques, medical practitioners could address suchblockages with the use of Tissue Plasminogen Activator (t-PA). However,t-PA must be used within the first three hours of the onset of strokesymptoms and may take hours or even days to successfully restore flow.In addition, t-PA carries an increased risk of intracerebral hemorrhage.It is currently believed that the use oft-PA results in a 30% successrate as well as a 6% major complication rate. In view of theselimitations, the majority of stroke patients in the U.S. do not receivet-PA treatment.

In addition, there are a number of surgical techniques used to removeblockages. For example, an embolectomy, involves incising a blood vesseland introducing a balloon tipped device (such as the Fogarty catheter)to the location of the occlusion. The balloon is then inflated at apoint beyond the clot and used to translate the obstructing materialback to the point of incision. The obstructing material is then removedby the surgeon. Concentric Medical, Inc. of Mountain View, Calif.supplies devices for an interventional approach to the removal ofobstructions. Concentric supplies a Merci® Retriever system as a devicebased approach for the removal of clots. This system engages andensnares a clot. Once captured, a balloon catheter inflates totemporarily halt forward blood flow while the clot is withdrawn. Theclot, is then pulled into the catheter and out of the body.

Typically, the existing means to remove obstructions do not address thefrictional forces that act on the obstruction during removal of theobstruction. For example, some conventional devices engage the clot fromthe distal (or downstream) side. As the device is pulled proximally (orupstream), the device attempts to either engulf or ensnare the clot.However, due to the consistency of the clot and because the clot istypically well lodged, within the vessel, the act of pulling, the clotin a proximal direction cause the clot to also compress in an axialdirection. This axial compression (when viewed along the axis of thevessel) causes a contemporaneous radial expansion of the clot (whenviewed relative to the vessel). As a result, the increase in diameter ofthe clot causes an increase in the frictional forces applied against thearterial wall. Thus, by not addressing the frictional forces acting onthe obstruction, the process of removing the clot may actually increasethe static force that would otherwise be required to remove or translatethe clot within the vessel. Unfortunately, increasing the amount offorce applied upon one side of the clot also increases the probabilityof complications during the procedure (e.g., fragmenting the clot,failing to remove the clot, failure to fully engulf/ensnare the clot,and/or device failure) and can cause potential damage to the surroundingvessel.

While there are other drugs and suppliers of devices for removal ofblockages, there remains a need for methods and devices that improve thesuccess rate and/or reduce the complication rate in restoring flow andthereby limit the damage from an ischemic stroke.

SUMMARY OF THE INVENTION

It should be noted that the present methods and devices may be used totreat blockages leading to ischemic stroke as well as to treat blockages(caused by “obstructions”) within other parts of the body (i.e., unlessspecifically noted, the devices and methods are not simply limited tothe cerebral vasculature). The term obstructions may include blood clot,plaque, cholesterol, thrombus, naturally occurring, foreign bodies(i.e., a part of the body that is lodged within the lumen), anon-naturally occurring foreign body (i.e., a portion of a medicaldevice or other non-naturally occurring substance lodged within thelumen.)

In one variation of the devices described herein, the device allows forsurrounding the obstruction prior to attempting to translate or move theobstruction within the vessel. It should be noted that although minimalaxial movement of the obstruction may take place, the device surroundsthe obstruction before such movement causes significant distortion tothe geometry of the obstruction resulting in an increase in the staticforce required to remove the obstruction from the vessel.

In another variation of the device, the device may include a lowfriction mode (such as a set of parallel wires, or wires extendingaxially along the lumen or vessel) that converts to an increasedfriction mode (such as a compressed set of wires acting on theobstruction or a twisted set of wires acting on the obstruction). Theincrease in friction is an increase in the friction between theobstruction and the device (as opposed to the vessel wall. In somecases, the low friction modes is a low surface area mode and the highfriction mode is a high surface area mode. When configured in the lowfriction mode, the device is better suited to engage the obstructionwithout the undesirable effect of prematurely mobilizing the obstructionor compacting the obstruction (e.g., when wires are slid across theobstruction in a transverse motion). Upon engaging the obstruction, thedevice will conform to a high friction mode with respect to theobstruction (in some cases the device will have an increased surfacearea mode). This high friction mode permits the device to better gripthe obstruction for ultimate removal of the obstruction.

The operation of the devices and method described herein secure theobstruction, overcome the elastic forces of the obstruction, then removethe obstruction from the anatomy without losing or fractionating theobstruction. In one variation of the invention, this is accomplished bythe obstruction removal device interacting with the obstruction in thefollowing manner: (1) the traversing filaments traverse the obstructionby passing either through the obstruction or between the obstruction andthe vascular wall; (2) the traversing portion is pulled proximally toengage the surrounding portion of the device around the obstruction, thesurrounding portion engaging the obstruction without causing significantmobilization of the obstruction; (3) the obstruction removal device ispulled further proximally and the surrounding portion now mobilizes theobstruction.

As shown below, variations of the devices have a configuration thatprovides a path for a portion of the device to surround the obstruction.The paths are made using traversing filaments that allow for lowfrictional translation of a surrounding portion of the device over theobstruction without causing axial translation of the obstruction. Thismechanism is described in more detail below.

Once in the proper position, a portion of the device (e.g., asurrounding portion) increases the frictional contact with theobstruction to disperse the pulling force more evenly across theobstruction. The increase points of contact allow for removal of theobstruction through tortuous anatomy while ensuring that the obstructionwill not escape the encapsulation.

The surrounding portion may be fabricated in a variety of ways. Forexample, the surrounding portion may comprise one or more filaments. Thesurrounding portion may comprise a filter/bag, a coil, helical filament,a mesh structure, corrugated sheet, braided filaments, single wound orcrossing filaments, tubes, membranes, films, solid wires, filled tubes,castings. Furthermore, the surrounding portion may have one or moreports, openings, slits, and/or holes. The surrounding portion may bemade by photochemical etching, mechanical drilling, weaving, braiding,laser cutting, or other means.

It should be noted that reference to surrounding or securing theobstruction includes partially and/or fully surrounding, engulfing,encapsulating, and/or securing the obstruction. In any case, thesurrounding portion engages the obstruction prior to translation of theobstruction within the lumen. As noted herein, a porn on of the devicemay convert into a surrounding section (e.g., when traversing wiresreorient to increase the friction acting on the obstruction).Accordingly, the traversing section converts into a surrounding section.

The various devices described herein rely on a reduced profile fordelivery and an expanded profile for ultimate removal of the clot. Thedevices, or components of the devices, may expand when released from aconstraint, which allows the device, or component, to assume apredetermined shape. Alternatively, or in combination, the devices maybe actuated to assume the expanded profiles. For example, the devicesmay be shape memory alloys that assume a profile when reaching apredetermined temperature (e.g., body temperature, or anothertemperature via delivery of energy to the shape memory alloy to triggera phase change). Actuation may also include use any expandable member(such as a coiled spring, balloon, wedge, etc.) that mechanically orfluidly forces expansion of the device. These modes are well known bythose skilled in the art and are intended to be within the scope of thedisclosure. When combined with the inventive concepts disclosed herein,such combinations fall within the inventive scope of this disclosure.

As noted above, the filaments of the invention may be used to translatethe device or may be used to form the surrounding; section. Accordingly,the filaments may be single wound or crossing filaments, tubes,membranes, films, solid wires, filled tubes, castings or any similarstructure. Moreover, the cross section of such filaments may vary asrequired (e.g., circular, oval, rectangular, square, or any such shape.)The filaments may be constructed from metals, polymers, composites,hydrogels, membranes, shape memory metals, shape memory polymers, orshape memory alloys, superelastic metals, superelastic polymers, orsuperelastic alloys, or combinations thereof. The filaments may haveuniform diameters or varying diameters. The characteristics of thefilament may be selected to better suit their required function. Forexample, they can be stiff, floppy, or even have different zones offlexibility. Moreover, the filaments may be braided or woven members, orthe construction may provide that the filaments cross at one or manypoints in an overlapping, interwoven, criss-crossing or similar manner.

It should be noted that in some variations of the invention, all or someof the filaments (used in the surrounding portion of the device) can bedesigned to increase their ability to adhere to the obstruction. Forexample, the filaments of the surrounding portion may be coupled to anenergy source (e.g., RF, ultrasonic, or thermal energy) to “weld” to theobstruction. Application of energy to the filaments may allow thesurrounding portion to deform into the obstruction and “embed” withinthe obstruction. Alternatively, the filaments may impart a positivecharge to the obstruction to partially liquefy the obstructionsufficiently to allow for easier removal. Alternatively, a negativecharge could be applied to further build thombus and nest the device forbetter pulling force. The filaments may be made stickier by use of ahydrophilic substance(s), or by chemicals that would generate a chemicalbond to the surface of the obstruction. Alternatively, the filaments mayreduce the temperature of the obstruction to congeal or adhere to theobstruction. The present brief description of the drawings

BRIEF DESCRIPTION OF THE DRAWINGS

Each of the following figures diagrammatically illustrates aspects ofthe invention. Variation of the invention from the aspects shown in thefigures is contemplated.

FIG. 1 illustrates a system for removing obstructions from body lumens.

FIG. 2A illustrates an example of an obstruction lodged within a bodylumen.

FIGS. 2B to 2F illustrate advancement of a catheter beyond anobstruction and placement of traversing wires around the obstruction.

FIG. 3A illustrates an obstruction removal device once converted to ahigh friction mode.

FIGS. 3B to 3E, show variations of a device having filaments that do notcross one another over the length of the obstruction when converted to ahigh friction mode.

FIG. 3F to 3G illustrate positioning a surrounding portion andtranslating the surrounding portion over the obstruction.

FIGS. 3H to 3I illustrate an obstruction removal device deployeddistally to an obstruction and then translated proximally over theobstruction.

FIGS. 4A to 4E illustrate various additional configurations of devicesable to assume a high friction mode covering over an obstruction.

FIG. 4F illustrates a variation of a device using an end of a catheterfor converting the device to a high friction mode.

FIG. 5A to 5B illustrate another variation of a portion of anobstruction removal device configured to convert from a low frictionmode to a high friction mode.

FIGS. 6A to 6G illustrate various configurations of connectors for usewith obstruction removal devices.

FIGS. 6H to 6I illustrate a variation of a leading wire and connectorhaving an unconstrained shape that is selected to be larger or simplydifferent than the intended vessel to provide increased, stability upondeployment.

FIG. 7A to 7D illustrates variations in which the connector is offset.

FIGS. 8A to 8B illustrate hooks, fibers, and/or barbs for increasing theability of the device to remove obstructions.

FIGS. 9A to 9C illustrate additional variations of obstruction removaldevices.

FIGS. 10A to 10H also illustrate additional variations of obstructionremoval devices, focusing mainly on variations of the surroundingportion.

FIGS. 11A to 11C illustrate a variation where use of mechanicalexpansion distends the vessel wall and loosens the obstruction from thevessel.

DETAILED DESCRIPTION

It is understood that the examples below discuss uses in the cerebralvasculature (namely the arteries). However, unless specifically noted,variations of the device and method are not limited to use in thecerebral vasculature. Instead, the invention may have applicability invarious parts of the body. Moreover, the invention may be used invarious procedures where the benefits of the method and/or device aredesired.

FIG. 1 illustrates a system 10 for removing obstructions from bodylumens as described herein. In the illustrated example, this variationof the system 10 is suited for removal of an obstruction in the cerebralvasculature. Typically, the system 10 includes a catheter 12microcatheter, sheath, guide-catheter, or simple tube/sheathconfiguration for delivery of the obstruction removal device to thetarget anatomy. The catheter should be sufficient to deliver the deviceas discussed below. The catheter 12 may optionally include an inflatableballoon 18 for temporarily blocking blood flow or for expanding thevessel to release the obstruction

It is noted that any number of catheters or microcatheters maybe used tolocate the catheter/microcatheter 12 carrying the obstruction removaldevice (not illustrated) at the desired target site. Such techniques arewell understood standard interventional catheterization techniques.Furthermore, the catheter 12 may be coupled to auxiliary or supportcomponents 14, 16 (e.g., energy controllers, power supplies, actuatorsfor movement of the device(s), vacuum sources, inflation sources,sources for therapeutic substances, pressure monitoring, flowmonitoring, various bio-chemical sensors, bio-chemical substance, etc.)Again, such components are within the scope of the system 10 describedherein.

In addition, devices of the present invention may be packaged in kitsincluding the components discussed above along with guiding catheters,various devices that assist in the stabilization or removal of theobstruction (e.g., proximal-assist devices that holds the proximal endof the obstruction in place preventing it from straying during removalor assisting in the removal of the obstruction), balloon-tipped guidecatheters, dilators, etc.

FIGS. 2A to 2F show one example of the deployment of the basic structureof connectors and traversing filaments about an obstruction in a vessel.The figures are intended to demonstrate the initial placement of theconnectors and filaments immediately prior to removal of the obstructioneither using a filter or by torquing, rotating and/or twisting the nearconnector relative to the far connector. This action converts the devicefrom a low friction device to a high friction device (where the low/highfriction is the friction between the device and the obstruction). Thisaction may also be referred to as a low surface area mode converting toa high surface area mode (in cases where the device extends beyond theobstruction and relative motion between ends of the device causes thedevice to shrink in axial length as it is twisted.) In addition, thenumber of connectors used, the shape of the connectors, as well as thenumber of filaments is intended to be for illustrative purposes only. Itis contemplated that any variation of connector and/or filament may bedeployed in a similar manner.

FIG. 2A illustrates an example of an obstruction 2 lodged within a bodylumen or vessel 6. In the case where the vessel is a cerebral artery,the obstruction may result in an ischemic stroke. Using standardinterventional catheterization techniques, a microcatheter 102 andguidewire 104 traverse the obstruction. The microcatheter 102 may beadvanced through the obstruction 2. Alternatively, the microcatheter 102may “push” aside the obstruction and is advanced around the obstruction.In any case, the microcatheter 102 travels from the near end 3 (orproximal side) of the obstruction 2 to the far end 4 (or distal side) ofthe obstruction 2. It is noted that the catheter 102 may be centered oroff-center with respect to the obstruction 2. Furthermore, the devicemay or may not be used with a guidewire to navigate to the site andtraverse the obstruction.

FIG. 2B shows another variation where a microcatheter 102 traverses theobstruction 2 between the wall of the vessel 6 and the obstruction 2. Asshown, the open end of the microcatheter 102 is distal to theobstruction 2 and is now positioned to deploy devices for removal of theobstruction 2. This variation shows the device after removal of anyguidewire. However, some variations of the device may be placed withoutan accompanying guidewire. Moreover, the structures discussed herein maybe directly incorporated into a guidewire assembly where deployment mayrequire a sheath or other covering to release the components fromconstraint.

FIG. 2C illustrates deployment of a far connector 110 from within themicrocatheter 102 distal to the obstruction 2. The far connector 110 canbe self-expanding such that it assumes, or moves towards, the expandedprofile as shown) upon deployment from the constraint of themicrocatheter 102.

The connectors 108, 110 and/or traversing filaments 112 are designed toexpand to the wall of the vessel when released from the catheter. Thisaction allows the device 100 to surround the obstruction 2 prior toattempting to dislodge it. The components of the obstruction removaldevice 100 (e.g., the leading wires 106, the connectors 108 110, thetraversing filaments 112, and/or the surrounding portion 114, may befabricated from any biocompatible material that permits the function asdescribed herein. In sonic variations, the material may comprise a shapememory or super-elastic alloy such as nitinol.

FIG. 2D shows withdrawal of the microcatheter 102 to the proximal side 3of the obstruction 2. The spacing between the far connector 110 and theobstruction 2 may vary. In some cases, the far connector 110 will movecloser towards the obstruction 2 during spacing of the traversing;filaments 112 as discussed below. The far connector 110 remains in placeeither using the inherent friction of the connector against the vesselsand/or obstruction 2. Alternatively, or in combination, a wire-typemember (not shown) may provide an opposing, force against the connector110 as the catheter 102 moves proximal to the obstruction 2.

As discussed herein, the obstruction removal devices include a pluralityof filaments affixed between connectors. Since the far connector 110 isdeployed at the distal side 4 of the obstruction 2, withdrawal of themicrocatheter 102 results in the plurality of filaments 112 spanningacross the obstruction 2 as shown.

FIG. 2E illustrates deployment of a near connector 108. Although theillustrated variation depicts the near connector 108 as being deployedfrom within the microcatheter 102, alternative variations of the deviceinclude a near connector 108 that is located about the exterior of themicrocatheter 102 or that is located about another delivery device (notshown) that is external to the microcatheter 102. In this case, the nearconnector 108 is similar in profile and design to the far connector 110.Accordingly, the near connector 108 self expands within the vessel 6upon deployment from the microcatheter 102. In some variations of thedevice, the near and far connectors 108, 110 may have different shapesor profiles. In any case, the profile of the connectors should besufficient to expand the traversing wires sufficiently within the vesselto prepare for ensnaring or encapsulation of the obstruction 2.

FIG. 2E also illustrates a connecting or leading wire/member 106 thatcouples the microcatheter 102 to the near connector 108. The termleading wire, leading member, lead wire, etc. is intended to encompass awire, tube, or any other structure that organizes and sometimes housesthe smaller traversing filaments and/or near connectors describedherein. Naturally, variations of the device include a leading wire 106that is affixed to the far connector or the traversing wires. Moreover,the illustration depicts a single leading wire 106. However, as notedbelow, the device can include a number of traversing wire 106 affixed tothe near and/or far connectors 108, 110.

FIG. 2F illustrates spacing the traversing filaments/wires 112 fromsimply spanning the obstruction 2 (as depicted in FIG. 2E). This actioncauses the filaments 112 to span the obstruction 2 while reorientingtowards an exterior of the obstruction 2. As noted herein, thetraversing filaments 112 may remain partially or fully within theobstruction 2. However, given that the filaments are spaced about theconnectors, the filaments shall separate radially over the obstructionallowing for the subsequent ensnaring and removal.

Spacing the filaments may occur via a number of modes such astensioning, expanding, spreading separating and/or withdrawing thefilaments. In certain variations of the device, the filaments aremoveable relative to a near connector and/or a far connector. Such afeature allows application of tension to the filaments while keeping theconnector in place. This causes the filament to enter a state of tensionfor spacing about the wall of the vessel. Alternatively, the filamentsmay be fixed relative to the connectors. Upon deployment, the filamentseither self expand or are actuated to space about the vessel wall foreventual translation of the device over the obstruction. Regardless ofthe mode used, the filaments are intended to be positioned at or near asurface of the obstruction so that they can reduce the effects of anyfriction between the obstruction and the lumen or vessel wall.

FIGS. 3A to 3I provide illustrations of device variations that ensnarethe obstruction 2 after the device is in the configuration demonstratedby FIG. 2F above. FIGS. 3A, 3C, and 3E represent variations of thedevice 100 after transforming from a low friction mode to a higherfriction mode for removal of the obstruction. FIGS. 3F and 3G illustratea variation Where a surrounding portion or filter covers the obstructionfor its ultimate removal from the body.

FIG. 3A illustrates rotation of the near connector 108 relative to thefar connector 110 to ensnare the obstruction 2 within the traversingwires 112. As noted herein, either connector may rotate while anotherconnector remains stationary. Alternatively, each connector may rotatewith the rate of rotation for one connector being, slower than another.In yet another variation, each connector may be rotated in oppositedirections.

Although the variation shows only four traversing, wires 112 any numberof wires may be used so long as the rotation converts the traversingwires 112 into a relatively increased friction mode as compared to thelow friction mode (when the traversing wires are in a parallelconfiguration). The low friction mode is represented by FIG. 2F. FIG. 3Aillustrates the obstruction removal device 100 after rotation of thesets of traversing filaments and connectors. The result is that theobstruction 2 becomes ensnared (and/or encapsulated) and may be removedfrom the body. It should be noted that the same effect may be achievedby only rotating one connector or set of wires while keeping the otherconnector or set of wires stationary.

The rotation of the connector 108 can be performed in any number of waysas known to those skilled in the art. However, as shown in FIG. 3A, thelead wire 106 may comprise additional secondary wires attached to theconnector 108. So rotation of the connector 108 may occur via rotationof the lead wire and/or microcatheter. In any case, once the deviceassumes the increased friction mode condition, the obstruction 2 can hemoved laterally within the vessel for removal.

FIGS. 3A to 3E illustrate various configurations where relative rotationof the connectors 108, 110 convert the device into a high friction mode.In FIG. 3A, the traversing filaments 112 twist and cross one anotherover the length of the obstruction 2. However, as shown in FIGS. 3B to3E, variations of the device 100 can have filaments 112 that do notcross one another over the length of the obstruction 2. Although thesevariations are depicted to have single connectors on each end and fourfilaments, the design of the devices may vary as required by theparticular application. In addition, the variations shown in FIGS. 3B to3E are shown without any catheter or leading wire for convenience tobetter illustrate the conversion of the device from a low friction modeto a high friction mode. Naturally, rotation of the catheter and/or leadwire will cause relative rotation between connectors.

In FIG. 3B, the device 100 is in a similar position as that shown inFIG. 2E. However, FIG. 3B shows a variation of a device 100 that isselected to have a length greater than the targeted obstruction 2. Uponrotation, the traversing filaments 112 remain uncrossed over the lengthof the obstruction 2. In some cases, the filaments 112 may experiencesome twisting and will not remain parallel. However, the filaments 112twist at twist points 116 that are proximal to and distal to theobstruction 2. The relative motion of the connectors 108, 110 as well asthe twist point 116 causes the filaments 112 to exert a compressiveforce on the obstruction 2 without crossing one another over the lengthof the construction. Accordingly, while the surface area in contactbetween the filaments 112 and obstruction 2 remains relatively the same,the compressive action of the filaments 112 onto the obstructionconverts the device 100 to a high friction mode on the obstruction.

FIG. 3D illustrates another variation of a device in a similar positionas that shown in FIG. 2E. However, FIG. 3D shows a variation of a device100 that extends proximally from the near end of the obstruction 2. Therelative motion between connectors 108. 110 causes a twist point 116that is proximal to the obstruction 2. As with the previous variation,the twist point 116 forces the filaments 112 against the obstruction 2without crossing one another over the length of the obstruction 2. As aresult, the device 100 is now in high friction mode. In some cases, thefilaments 112 may experience some twisting and will not remain parallel.

The variation of FIGS. 3D and 3E also show the device 100 as including acap or cover 118 about the distal connector 110. The cap or cover 118may be a bag, mesh, a continuation of the filaments 112, and/or asurrounding, portion 114 as discussed herein. The cap or cover 118reduces the likelihood that the obstruction is driven through the farconnector 110 during conversion of the device 100 from a low frictionmode to a high friction mode.

FIG. 3F illustrates another variation of a device where the farconnector 110 includes a filter or surrounding; portion 114. Invariations of the device, the filter 114 is sufficiently permeable toallow blood flow therethrough. As noted above, the surrounding portion114 may be any structure that covers, encapsulates, engulfs, and/orensnares the obstruction either fully or partially. Accordingly,although the surrounding portion 114 is illustrated as a filter/bag, thesurrounding portion 114 may comprise a coil, helical wire, a pluralityof filaments, mesh structure, corrugated sheet, braided filaments,single wound or crossing filaments, tubes, filled tubes, castings, solidwires, membranes, films, capturing sections, (and may include ports,openings, slits, and/or holes made from photochemical etching,mechanical drilling) or any other structure that may translate or removethe obstruction 2 once the frictional component is addressed.

In this variation, the obstruction removal device 100 includes leadingfilaments 106 connected to a near connector 108. In this example, thelead filament 106 may be a single wire or filament. Alternatively, thelead filament may comprise a single wire with a plurality of wiresconnecting the single wire to the ring.

As with the above examples, the illustrated variation shows theconnector 108 as comprising a loop. However, as described herein, theconnectors may also comprise various alternate shapes (e.g., a circle,an arcuate shape, a partial circular shape, a loop, an oval, a square, arectangle, a polygon, an overlapping loop, a pair of semi-circles, aflower shape, and a FIG. 8, other shapes, etc.) The near connector 108is joined to a far connector 110 via a plurality of filaments 112. It isnoted that the inventive device shall include at least one, butpreferably two or more traversing filaments 112. It is further notedthat the obstruction removal device 100 may he part of or integratedwith the microcatheter 102.

FIG. 3G illustrates withdrawal of the microcatheter 102 and the proximaltranslation of device 100 to place the surrounding portion 114 over theobstruction 2. As the obstruction removal device 100 translatesproximally, the traversing filaments 112 locate towards the exteriorregion of the obstruction 2. As discussed above, the connectors 108, 110and traversing filaments 112 are designed to expand to (or near to) theperimeter of the wall of the vessel 2 and will usually locate to anexterior of the obstruction 2. However, variations of the device andmethod include situations where the filaments locate substantially, butnot fully, towards the outer region of the obstruction. In any case, thelocation of the filaments 112 will sufficiently overcome the frictionalforces discussed herein. In the illustrated variation, the traversingfilaments 112 substantially span the length of the obstruction 2 byextending across the (proximal) 3 and (distal) 4 sides. These traversingfilaments 112 provide paths for movement of the device 100 around theobstruction 2. These paths allow for the surrounding portion 114 toengulf the entire obstruction 2 so that it may be removed from thevasculature and body.

FIG. 3H depicts an obstruction removal device 100 similar to that shownin FIG. 3F. However, in this variation, the near and far connectors 108,110 are both deployed distally to the obstruction 2 and then translatedback over the obstruction 2. As shown, this deployment allows thetraversing filaments 112 and the surrounding portion 114 to separateprior to contacting the occlusion 2. Next, the entire device 100 ispulled over the occlusion 2 as described above. The variation of thedevice shown in FIGS. 3F and 3H addresses the frictional forces that actbetween the obstruction and the vessel wall. Conventional devices thatprovide a bag attached to a wire (such as a vascular filter or distalprotection device), are typically unable to remove the obstructionbecause they cannot overcome these frictional forces that lodge the clotagainst the vessel wall. Typically, such conventional devices are onlydesigned to “catch” free floating clots. The traversing filamentsdescribed herein are configured to be positioned surrounding theobstruction. Their low friction with respect to the clot and the vesselallows for positioning of the filaments without disrupting or furthercompacting the clot against the vessel wall. Once the filaments surroundor are spaced about the obstruction, they reduce the friction betweenthe clot and vessel wall by reducing points of contact. Once thesefilaments surrounded the clot, they permit translation of the device topermit an encapsulating section 114 to surround the obstruction forremoval.

FIG. 3I illustrates the device 100 of FIG. 3H when translated over theobstruction 2. Eventually, the device 100 is pulled so that thesurrounding portion or blood permeable filter 114 covers the obstruction2 (as shown in FIGS. 3F arid 3G.

FIG. 4A illustrates another variation of a portion of an obstructionremoval device 120 that is able to convert from a low friction modecovering to a higher friction mode covering. As noted above, thisvariation allows the medical practitioner to engage an obstruction withsparse coverage or low friction mode to overcome frictional forces. Uponproperly engaging the obstruction, the device configuration allowsconversion to a high friction mode for removal of the device andobstruction.

As shown, this variation of the obstruction removal device 120 includestwo sets of traversing filaments 122, 124 and accompanying connectors108, 110, and 126, 128. The first set 122 comprises a first nearconnector 108 and first far connector 110 with the accompanyingtraversing filaments. The second set 124 comprises the second nearconnector 126 and second far connector 128 with the accompanyingtraversing filaments 124. The second set 124 is coaxially located overthe first set 122. The materials of the components may be as describedabove. In any case, the components are designed to expand to theperimeter of the vessel wall upon release from the catheter.

FIG. 4B shows the conversion of the obstruction removal deviceconverting from a low friction mode (from FIG. 4A) to the high frictionmode. For example, the first near connector 108 may be rotated relativeto the second near connector 126 (where the second near connector mayremain still or it may be rotated in an opposite direction relative tothe first near connector as shown by the arrows). As a result, thetraversing filaments 122, 124 deform in opposite directions to form abraid-type pattern increasing the friction mode over the obstruction.

FIG. 4C illustrates another variation of an obstruction removal device100 in a low friction mode state. In this variation, the device 100includes a near connector 108, a far connector 110 with traversingfilaments between the connectors 108, 110. The device 100 also includesan additional connector 132 with non-rotating filaments 134 extending tothe far connector 110. FIG. 4D illustrates the device 100 of FIG. 4Cwhen the near connector 108 is rotated as shown by arrow 136. However,the additional connector 132 and associated filaments 134 do not rotate.Upon rotation of the near connector 108 and twisting of the filaments112, all of the filaments 112 and 134 compress the obstruction over thelength of the filaments. Such a feature creates additional friction onthe obstruction by the device.

FIG. 4E shows another variation of an obstruction removal device 100configured to move between low and high friction mode states. Thisvariation includes additional support rings 138 located betweenconnectors 108, 110 and within the filaments 112. The support rings keepthe device 100 at a relatively constant diameter upon assuming theincreased friction mode state. The support rings may be slightlyundersized compared to the connectors, allowing the filaments toslightly compress the obstruction when converted to a high frictionmode, but limiting the amount of compression by limiting the resultingdiameter. The support rings 138 can be freely placed within thetraversing filaments 112. Alternatively, the rings 138 can be attachedto one or more than one filament 112 to prevent undesired migrationduring deployment of the device.

FIG. 4F illustrates one example of a microcatheter 102 having a nearconnector 108 located externally to the catheter 102 with traversingfilaments 112 extending out of the catheter and through the connector108. In this variation, rotation or torquing of the catheter 102 twiststhe filaments 112 resulting in increased friction mode of the filaments112 over an obstruction. FIG. 4F illustrates an additional connector 132having stationary filaments 134. This variation of the device includesthe external connector 108 directly coupled to a far connector notshown.)

FIG. 5A illustrates a variation of the device 120 having only connectors108 at one side of the device 120. In this variation, the device 120 maystill include two sets 108, 122 of connectors and two sets of traversingfilaments 112, 124. FIG. 5B illustrates the variation of FIG. 5A afterconversion to a high friction mode over the obstruction 2. As discussedherein, the connectors may be other structures than loops. Moreover,variations of the invention include connectors that may be drawn down toa smaller size to facilitate removal from the body after securing theobstruction. This may be accomplished by torquing: the device or panthereof, by re-sheathing part or all of the device, or by any mechanicalmeans designed into the features of the device itself. Any of theseactions, or combination thereof, may also serve to compress or decreasethe diameter of the obstruction itself to facilitate removal from thebody.

In another variation, the devices described herein may be assembled orconstructed in-situ. For example, components of the device may includeconnectors, portions of the connectors, traversing elements, and/orsurrounding sections. Any combination of these components can be placedin sequential fashion. Doing so forms a completed structure fromdeployment of a number of individual components. The end result is theformation of a device as shown in the figures. Accordingly, suchcomponents of the device may be separately deployed in a manner thatrequires “assembly” of the components by a medical practitioner duringthe procedure.

FIGS. 6A-6G illustrate variations of the connectors 108, 110. FIG. 6Ashows a loop-shaped connector 108, 110 having attachment points 140 forthe filaments (not shown). As noted above, the connectors can beself-expanding or actuated to expand. The connectors may be fabricatedfrom a polymer, a shape memory metal, polymer, or alloy, a super-elasticmetal, polymer, or alloy, or any type of acceptable medical grade alloy,polymer, or composite structure. Also, the devices described herein canbe fabricated from solid material, sheet or film, hollow or solid orfilled rod or wire, braids, coils, etc. In the case of the polymer,additional strength may be added by constructing a composite layereddevice. For example, a hydrogel polymer with a hydrophilic fiber netinside that acts as exoskeleton to strengthen underlying polymer. Asdiscussed herein, some variations of the device may include a distalconnector having a cap or cover to prevent the obstruction from escapingas the device is removed. Furthermore, the sizing of the connectorswithin the vessel can assist in controlling relative rotation betweenconnectors. For example, as a connector moves towards its expanded shapeand engages a vessel or lumen wall, the rotational friction between theconnector and lumen wall may prevent rotation. Accordingly, an adjacentconnector may have a smaller expanded profile so that the connectorexperiences less friction when rotated.

FIG. 6A also illustrates the connector as having attachment points 140for coupling the filaments to the connectors. These attachment pointsmay allow for movement of the filaments relative to the connector totension or separate the connectors (as described above.) The filamentsmay also be coupled such that they are fixed relative to the connectors.In such a case, pulling of the lead wire will cause the entire assembly(e.g., connectors, filaments, and/o surrounding portion) to translatethrough the vessel.

FIGS. 6B through 6G show various configurations of connectors for use inthe present device. The connectors may be cut from sheets, fabricatedfrom wire, molded, stamped, laser cut, photo or chemically etched, orfabricated in any other customary manner. Moreover, the connectors 108,110 shown may be used in the near and/or far ends of the traversingwires Different connector profiles may be incorporated into the device.In most cases, as shown, the connectors will form an arcuate shape sothat they can expand against a vessel wall without causing trauma to thevessel. To illustrate the connector configurations, FIGS. 6B to 6E areshown without any accompanying traversing filaments.

FIG. 6B shows a connector 108, 110 that is a loop shape as shown above.However, alternative configurations include a discontinuous profile, asillustrated in FIG. 6C and an overlapping profile, as illustrated inFIG. 6D. Such constructions allows the connector to adjust to varyingdiameters of body lumens. It is noted that a device may comprise loopsof either construction. It should be also noted that although loops areshown, other variations may work equally well. Variations of theinvention include connectors that may be drawn down to a smaller size tofacilitate removal from the body once the obstruction is secured. Thismay be accomplished by torquing the device or part thereof, byre-sheathing part or all of the device or by any mechanical meansdesigned into the features of the device itself. Any of these actions,or combination thereof, may also serve to compress or decrease thediameter of the obstruction itself to facilitate removal from the body.In addition, the overlapping connector, as shown in FIG. 6D, may includea sliding ring type fastener that allows the overlapping connector loopto expand in the same plane.

In another example, the device may be fabricated from a polymercomposite that makes up the fasteners, filaments, bags, etc. where thepolymeric composite is very floppy until it is exposed to either thebody fluids and or some other delivered activator that causes thepolymer to further polymerize or stiffen for strength. Various coatingscould protect the polymer from further polymerizing before the device isproperly placed. The coatings could provide a specific duration forplacement (e.g., 5 minutes) after which the covering degrades or isactivated with an agent (that doesn't affect the surrounding tissues)allowing the device to increase in stiffness so that it doesn't stretchas the thrombus is pulled out. For example, shape memory polymers wouldallow the device to increase in stiffness.

FIG. 6E shows a connector 108, 110 having multiple sections 146. Asnoted above, the connector sections 146 are arcuate shaped to minimizetrauma to a vessel wall. However, other shapes are also intended to bewithin the scope of this disclosure.

FIGS. 6B through 6G also illustrate various configurations of leadingwires 106. The connectors may have any number of leading wires. In somevariations, it may be desirable to space the leading wires about theprofile of the connector to aid in uniform movement of the device as itis pulled over the obstruction in the vessel.

FIGS. 6F and 6G illustrate additional variations of leading wires 106comprising shaped wire structures that form a “c” portion 142 of theconnector. In one variation, when constrained the “c” shaped portions142 move together to allow for deliver within the catheter. Upon releasefrom the catheter, the portions 142 assume their resting shape andexpand within the vessel. The connecting portions 142 can be selected tohave a size that is slightly greater than that of the vessel. Sizing thedevice relative to the target vessel may assist in placing theconnecting portions 142 and accompanying traversing wires 112 againstthe wall of the vessel.

FIG. 6G shows an additional variation where a portion 144 of a leadingwire 106 also has a “c” or semi-circular shape. In this configuration,the “c” shaped portion 144 of the leading wire 106 can also be sizedrelative to the target vessel. Accordingly, the portion 144 of theleading wire 106 functions to drive the connecting portion 142 againstthe vessel wall, while the shape of the connecting portion 142 alsodrives the traversing wire 112 against the vessel wall.

FIG. 6H illustrates another variation of a leading wire 106 having anunconstrained shape that is selected to be larger than the intendedvessel or simply different than a cross sectional profile of theintended vessel (i.e., not circular or tubular, but e.g., linear orother different shape). In this variation, the leading wire 106 hasportions 144 that extend in opposite directions. This configuration isintended for illustrative purposes only. Variations include connectingportions pointing in an orthogonal direction from the main lead wire106, oblique, parallel as shown), or a combination thereof. In any case,the unconstrained shape is intended to have a larger profile or sizethan the intended vessel. Moreover, the unconstrained shape may have anentirely different profile than the intended vessel. As shown in thefigures, the profile of the device extends radially from the vessel. Sowhen the device and leading wire are released, the leading wire attemptsto return to the unconstrained shape. In those variations where theunconstrained shape is different from the circular profile of thevessel, the leading, wire assumes a shape that accommodates the vesselbut is more rigid and stable since its unconstrained shape is entirelydifferent from that of the vessel.

FIG. 6I shows the same device of FIG. 6H when released from amicrocatheter, sheath, or tube when in the vessel. Once released, theleading wire 106 and accompanying portions 144 attempt to revert to theunconstrained shape (as shown in FIG. 6H). However, the vessel 6restrains the leading wire 106 and portions 144 such that the portions144 act on the walls of the vessel. This feature allows for improvedstability when deploying the leading wires and attached connectors andfilaments within the vessel.

FIGS. 7A through 7C illustrate variations of connectors 108, 110 wherethe connector portions are axially spaced by an offset 152. One benefitof placing the connector portions 142, 146 in different planes is thatthe device may be delivered via a smaller microcatheter because theconnector portions may be collapsed to a smaller diameter. FIG. 7Aillustrates an offset 152 between connector portions 142 where eachportion 142 is coupled to leading wires 148, 150 of varying lengths.FIG. 7B illustrates connector portions 146 spaced axially along aleading wire 106 to provide a gap 152. FIG. 7C illustrates a connector108, 110 having multiple components 146 where one or more components isaxially spaced to provide a gap 152. FIG. 7D shows a variation 108, 110having a flower shape where each connector portion 146 is lion-planarsuch that the gap 152 occurs over the length of the connector portion146.

Another aspect applicable to all variations of the devices is toconfigure the devices (whether the traversing filament or thesurrounding portion) for better adherence to the obstruction. One suchmode includes the use of coatings that bond to certain clots (or othermaterials causing the obstruction.) For example, the traversing filamentand/or surrounding portion may be coated with a hydrogel or adhesivethat bonds to a thrombus. Accordingly, as the surrounding portion coversthe clot, or as the device twists about the clot, the combination of theadditive and the mechanical structure of the device may improve theeffectiveness of the device in removing the obstruction.

Such improvements may also be mechanical or structural. For example, asshown in FIG. 8A, the traversing members may have hooks, fibers, orbarbs 154 that grip into the obstruction when the device converts to ahigh friction mode. The hooks, fibers, or barbs 154 may also beincorporated into the surrounding portion. However, it will be importantthat such features do not hinder the ability of the practitioner toremove the device from the body. For example, FIG. 8B illustrates amagnified view of the area 8B from FIG. 8A. As illustrated, the barbsmay be configured such that rotation in a particular direction causesthe barbs to adhere to the obstruction. Such a configuration could alsoallow lateral movement, without the barbs interfering with the vessel.

In addition to additives, the device can be coupled to an RF or otherpower source such as 14 or 16 in FIG. 1), to allow current, ultrasoundor RF energy to transmit through the device and induce clotting or causeadditional coagulation of a clot or other the obstruction.

The methods described herein may also include treating the obstructionprior to attempting to remove the obstruction. Such a treatment caninclude applying a chemical or pharmaceutical agent with the goal ofmaking the occlusion shrink or to make it more rigid for easier removal.Such agents include, but are not limited to chemotherapy drugs, orsolutions, a mild formalin or aldehyde solution.

Although not illustrated, the devices and methods described herein mayalso be useful in removing obstructions lodged within bifurcations inthe anatomy. Generally, bifurcations greatly increase the frictionalforces on the obstructions since the obstruction tends to be lodged inboth branching sections of the bifurcation. In such cases, the use ofthe presently described devices and methods may also include anadditional “puller” device that advances beyond the portion of theobstruction partially located in the bifurcated vessel.

As for other details of the present invention, materials andmanufacturing techniques may be employed as within the level of thosewith skill in the relevant art. The same may hold true with respect tomethod-based aspects of the invention in terms of additional acts thatare commonly or logically employed. In addition, though the inventionhas been described in reference to several examples, optionallyincorporating various features, the invention is not to be limited tothat which is described or indicated as contemplated with respect toeach variation of the invention.

FIGS. 9A through 9C illustrate additional variations of obstructionremoval devices. In these variations, the traversing filaments 112 maycomprise a mesh of wires or single connector. FIGS. 9A to 9B illustratea variation in which the connector 108 comprises a wire rather than aloop. However, the filaments and connectors should be configured toexpand to the perimeter of the vessel wall as described previously.

FIGS. 10A-10H illustrate various additional embodiments of obstructionremoval devices 130 according to the present invention. In thesevariations, the connector 108 may form a rigid wire or hard polymer toassist in placement of the device 130. The surrounding portion 132 maybe fabricated from less rigid filaments that increase the point ofcontact with the obstruction. The surrounding portion may also havefilaments that undergo a phase change from non-rigid for less rigid) torigid.

It should be noted that any number of traversing filaments 112 or setsmay be used in these variations.

In additional aspect of the invention, as shown in FIG. 11A to 11C, themethods and or devices may include expansion of the vessel wall adjacentto the obstruction either with a balloon, coil, or similar mechanicalexpansion means, drugs, fluids, etc. Such an improvement may aid wherethe obstruction expands part, of the vessel wall thereby increasing theamount of force required for displacement. By distending the vessel wallas described above, the forces on the obstruction may he reducedallowing for ease of removal. FIG. 11A illustrates an obstruction 2embedded within the vessel 6. FIGS. 11B to 11C illustrate variationswhere use of a coil (FIG. 11B) or a non-distensible balloon 162 (FIG.11C) proximal to the obstruction 2 distends the vessel wall to loosenthe obstruction 2 from the vessel. Accordingly, devices (whetherdescribed, herein or other conventional devices) may then remove theobstruction 2.

In those variations with a mechanical expansion means, the expansionmeans may be located on the delivery catheter of the obstruction removaldevice, on a wire member of the device, and/or on a separate catheter orwire used in combination with the first delivery catheter. However,variations of such configurations are within the scope of the invention.

In addition, devices and methods described herein may also use balloonsproximal to the obstruction to stop or slow blood flow therebypreventing the blood from dislodging part or all of the obstruction.

Various changes may be made to the invention described and equivalents(whether recited herein or not included for the sake of some brevity)may be substituted without departing from the true spirit and scope ofthe invention. Also, any optional feature of the inventive variationsmay be set forth and claimed independently, or in combination with anyone or more of the features described herein. Accordingly, the inventioncontemplates combinations of various aspects of the embodiments orcombinations of the embodiments themselves, where possible. Reference toa singular item, includes the possibility that there are plural of thesame items present. More specifically, as used herein and in theappended claims, the singular forms “a,” “and,” “said,” and “the”include plural references unless the context clearly dictates otherwise.

I/We claim:
 1. An intravascular apparatus for removing an obstructionfrom a vessel of a patient, the device comprising: a microcatheterhaving a size and flexibility to navigate within a neurovascular regionof the patient; a near connector having a first expanded profile whenunconstrained, such that on deployment in the vessel the near connectorexpands towards the first expanded profile; a far connector beingcollapsible to fit within the microcatheter and having a second expandedprofile when unconstrained, such that on deployment in the vessel thesecond connector expands towards the second expanded profile; at leastone lead filament coupling the near connector to the microcatheter; anda plurality of traversing filaments extending between the near and farconnectors, and spaced apart on each connector such that spacing thetraversing filaments causes the filaments to move towards a wall of thevessel.
 2. The intravascular apparatus of claim 1, further comprising ablood permeable member affixed to the far connector, the blood permeablefilter being collapsible to fit within the microcatheter.
 3. Theintravascular apparatus of claim 2, where the blood permeable membercomprises a structure selected from the group consisting of a basket, afilter, a bag, a coil, a helical wire structure, a mesh, a corrugatedsheet, braided wires, a single wound wire, a plurality of crossingwires, a tube, a membrane, and a film.
 4. The intravascular apparatus ofclaim 2, further comprising a plurality of hook shaped members locatedon the blood permeable member.
 5. The intravascular apparatus of claim1, further comprising a third connector located adjacent to the nearconnector, and a plurality of non-rotating filaments extending betweenthe far connector and the third connector, where the first connector isrotatable relative to the far and third connectors to cause theplurality of traversing filaments to form a mesh pattern.
 6. Theintravascular apparatus of claim 1, where the near and far connectorsare rotatable relative to each other to cause at least a section of theplurality of filaments to cross one another.
 7. The intravascularapparatus of claim 6, where the near connector is stationary and the farconnector is rotatable.
 8. The intravascular apparatus of claim 6, wherethe far connector is stationary and the near connector is rotatable. 9.The intravascular apparatus of claim 6, where the far connector and thenear connector are rotatable in opposite directions.
 10. Theintravascular apparatus of claim 1, where the near connector comprises ashape selected from a circle, an arcuate shape, a partial circularshape, a loop, an oval, a square, a rectangle, a polygon, an overlappingloop, a pair of semi-circles, a clover shape, and a FIG.
 8. 11. Theintravascular apparatus of claim 1, where the far connector comprises ashape selected from an arcuate shape, a partial circular shape, a loop,an oval, a square, a rectangle, a polygon, an overlapping loop, a pairof semi-circles, a clover shape, and a FIG.
 8. 12. The intravascularapparatus of claim 1, further comprising a plurality of hook shapedmembers located on at least one filament.
 13. The intravascularapparatus of claim 1, where the near connector is collapsible to fitwithin the microcatheter.
 14. The intravascular apparatus of claim 1,where the near connector is affixed to an exterior of the microcatheter.15. The intravascular apparatus of claim 1, where the near connectorcomprises a plurality of near connector portions.
 16. The intravascularapparatus of claim 15, where at least one of the near connector portionsis axially spaced from another near connector portion.
 17. Theintravascular apparatus of claim 1, where the far connector comprises aplurality of far connector portions.
 18. The intravascular apparatus ofclaim 17, where at least one of the far connector portions is axiallyspaced from another far connector portion.
 19. The intravascularapparatus of claim 1, further comprising at least one support ringwithin the filament.
 20. The intravascular apparatus of claim 1, wherethe near connector, the lead filament, and the plurality of traversingfilaments are collapsible to fit within the microcatheter and areself-expanding upon deployment from the microcatheter.